1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Kerberos-based RxRPC security 3 * 4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <crypto/skcipher.h> 11 #include <linux/module.h> 12 #include <linux/net.h> 13 #include <linux/skbuff.h> 14 #include <linux/udp.h> 15 #include <linux/scatterlist.h> 16 #include <linux/ctype.h> 17 #include <linux/slab.h> 18 #include <linux/key-type.h> 19 #include <net/sock.h> 20 #include <net/af_rxrpc.h> 21 #include <keys/rxrpc-type.h> 22 #include "ar-internal.h" 23 24 #define RXKAD_VERSION 2 25 #define MAXKRB5TICKETLEN 1024 26 #define RXKAD_TKT_TYPE_KERBEROS_V5 256 27 #define ANAME_SZ 40 /* size of authentication name */ 28 #define INST_SZ 40 /* size of principal's instance */ 29 #define REALM_SZ 40 /* size of principal's auth domain */ 30 #define SNAME_SZ 40 /* size of service name */ 31 #define RXKAD_ALIGN 8 32 33 struct rxkad_level1_hdr { 34 __be32 data_size; /* true data size (excluding padding) */ 35 }; 36 37 struct rxkad_level2_hdr { 38 __be32 data_size; /* true data size (excluding padding) */ 39 __be32 checksum; /* decrypted data checksum */ 40 }; 41 42 static int rxkad_prime_packet_security(struct rxrpc_connection *conn, 43 struct crypto_sync_skcipher *ci); 44 45 /* 46 * this holds a pinned cipher so that keventd doesn't get called by the cipher 47 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE 48 * packets 49 */ 50 static struct crypto_sync_skcipher *rxkad_ci; 51 static struct skcipher_request *rxkad_ci_req; 52 static DEFINE_MUTEX(rxkad_ci_mutex); 53 54 /* 55 * Parse the information from a server key 56 * 57 * The data should be the 8-byte secret key. 58 */ 59 static int rxkad_preparse_server_key(struct key_preparsed_payload *prep) 60 { 61 struct crypto_skcipher *ci; 62 63 if (prep->datalen != 8) 64 return -EINVAL; 65 66 memcpy(&prep->payload.data[2], prep->data, 8); 67 68 ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC); 69 if (IS_ERR(ci)) { 70 _leave(" = %ld", PTR_ERR(ci)); 71 return PTR_ERR(ci); 72 } 73 74 if (crypto_skcipher_setkey(ci, prep->data, 8) < 0) 75 BUG(); 76 77 prep->payload.data[0] = ci; 78 _leave(" = 0"); 79 return 0; 80 } 81 82 static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep) 83 { 84 85 if (prep->payload.data[0]) 86 crypto_free_skcipher(prep->payload.data[0]); 87 } 88 89 static void rxkad_destroy_server_key(struct key *key) 90 { 91 if (key->payload.data[0]) { 92 crypto_free_skcipher(key->payload.data[0]); 93 key->payload.data[0] = NULL; 94 } 95 } 96 97 /* 98 * initialise connection security 99 */ 100 static int rxkad_init_connection_security(struct rxrpc_connection *conn, 101 struct rxrpc_key_token *token) 102 { 103 struct crypto_sync_skcipher *ci; 104 int ret; 105 106 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key)); 107 108 conn->security_ix = token->security_index; 109 110 ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); 111 if (IS_ERR(ci)) { 112 _debug("no cipher"); 113 ret = PTR_ERR(ci); 114 goto error; 115 } 116 117 if (crypto_sync_skcipher_setkey(ci, token->kad->session_key, 118 sizeof(token->kad->session_key)) < 0) 119 BUG(); 120 121 switch (conn->security_level) { 122 case RXRPC_SECURITY_PLAIN: 123 case RXRPC_SECURITY_AUTH: 124 case RXRPC_SECURITY_ENCRYPT: 125 break; 126 default: 127 ret = -EKEYREJECTED; 128 goto error; 129 } 130 131 ret = rxkad_prime_packet_security(conn, ci); 132 if (ret < 0) 133 goto error_ci; 134 135 conn->rxkad.cipher = ci; 136 return 0; 137 138 error_ci: 139 crypto_free_sync_skcipher(ci); 140 error: 141 _leave(" = %d", ret); 142 return ret; 143 } 144 145 /* 146 * Work out how much data we can put in a packet. 147 */ 148 static int rxkad_how_much_data(struct rxrpc_call *call, size_t remain, 149 size_t *_buf_size, size_t *_data_size, size_t *_offset) 150 { 151 size_t shdr, buf_size, chunk; 152 153 switch (call->conn->security_level) { 154 default: 155 buf_size = chunk = min_t(size_t, remain, RXRPC_JUMBO_DATALEN); 156 shdr = 0; 157 goto out; 158 case RXRPC_SECURITY_AUTH: 159 shdr = sizeof(struct rxkad_level1_hdr); 160 break; 161 case RXRPC_SECURITY_ENCRYPT: 162 shdr = sizeof(struct rxkad_level2_hdr); 163 break; 164 } 165 166 buf_size = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN); 167 168 chunk = buf_size - shdr; 169 if (remain < chunk) 170 buf_size = round_up(shdr + remain, RXKAD_ALIGN); 171 172 out: 173 *_buf_size = buf_size; 174 *_data_size = chunk; 175 *_offset = shdr; 176 return 0; 177 } 178 179 /* 180 * prime the encryption state with the invariant parts of a connection's 181 * description 182 */ 183 static int rxkad_prime_packet_security(struct rxrpc_connection *conn, 184 struct crypto_sync_skcipher *ci) 185 { 186 struct skcipher_request *req; 187 struct rxrpc_key_token *token; 188 struct scatterlist sg; 189 struct rxrpc_crypt iv; 190 __be32 *tmpbuf; 191 size_t tmpsize = 4 * sizeof(__be32); 192 193 _enter(""); 194 195 if (!conn->key) 196 return 0; 197 198 tmpbuf = kmalloc(tmpsize, GFP_KERNEL); 199 if (!tmpbuf) 200 return -ENOMEM; 201 202 req = skcipher_request_alloc(&ci->base, GFP_NOFS); 203 if (!req) { 204 kfree(tmpbuf); 205 return -ENOMEM; 206 } 207 208 token = conn->key->payload.data[0]; 209 memcpy(&iv, token->kad->session_key, sizeof(iv)); 210 211 tmpbuf[0] = htonl(conn->proto.epoch); 212 tmpbuf[1] = htonl(conn->proto.cid); 213 tmpbuf[2] = 0; 214 tmpbuf[3] = htonl(conn->security_ix); 215 216 sg_init_one(&sg, tmpbuf, tmpsize); 217 skcipher_request_set_sync_tfm(req, ci); 218 skcipher_request_set_callback(req, 0, NULL, NULL); 219 skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x); 220 crypto_skcipher_encrypt(req); 221 skcipher_request_free(req); 222 223 memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv)); 224 kfree(tmpbuf); 225 _leave(" = 0"); 226 return 0; 227 } 228 229 /* 230 * Allocate and prepare the crypto request on a call. For any particular call, 231 * this is called serially for the packets, so no lock should be necessary. 232 */ 233 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call) 234 { 235 struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base; 236 237 return skcipher_request_alloc(tfm, GFP_NOFS); 238 } 239 240 /* 241 * Clean up the crypto on a call. 242 */ 243 static void rxkad_free_call_crypto(struct rxrpc_call *call) 244 { 245 } 246 247 /* 248 * partially encrypt a packet (level 1 security) 249 */ 250 static int rxkad_secure_packet_auth(const struct rxrpc_call *call, 251 struct rxrpc_txbuf *txb, 252 struct skcipher_request *req) 253 { 254 struct rxkad_level1_hdr *hdr = (void *)txb->data; 255 struct rxrpc_crypt iv; 256 struct scatterlist sg; 257 size_t pad; 258 u16 check; 259 260 _enter(""); 261 262 check = txb->seq ^ ntohl(txb->wire.callNumber); 263 hdr->data_size = htonl((u32)check << 16 | txb->len); 264 265 txb->len += sizeof(struct rxkad_level1_hdr); 266 pad = txb->len; 267 pad = RXKAD_ALIGN - pad; 268 pad &= RXKAD_ALIGN - 1; 269 if (pad) { 270 memset(txb->data + txb->offset, 0, pad); 271 txb->len += pad; 272 } 273 274 /* start the encryption afresh */ 275 memset(&iv, 0, sizeof(iv)); 276 277 sg_init_one(&sg, txb->data, 8); 278 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 279 skcipher_request_set_callback(req, 0, NULL, NULL); 280 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 281 crypto_skcipher_encrypt(req); 282 skcipher_request_zero(req); 283 284 _leave(" = 0"); 285 return 0; 286 } 287 288 /* 289 * wholly encrypt a packet (level 2 security) 290 */ 291 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call, 292 struct rxrpc_txbuf *txb, 293 struct skcipher_request *req) 294 { 295 const struct rxrpc_key_token *token; 296 struct rxkad_level2_hdr *rxkhdr = (void *)txb->data; 297 struct rxrpc_crypt iv; 298 struct scatterlist sg; 299 size_t pad; 300 u16 check; 301 int ret; 302 303 _enter(""); 304 305 check = txb->seq ^ ntohl(txb->wire.callNumber); 306 307 rxkhdr->data_size = htonl(txb->len | (u32)check << 16); 308 rxkhdr->checksum = 0; 309 310 txb->len += sizeof(struct rxkad_level2_hdr); 311 pad = txb->len; 312 pad = RXKAD_ALIGN - pad; 313 pad &= RXKAD_ALIGN - 1; 314 if (pad) { 315 memset(txb->data + txb->offset, 0, pad); 316 txb->len += pad; 317 } 318 319 /* encrypt from the session key */ 320 token = call->conn->key->payload.data[0]; 321 memcpy(&iv, token->kad->session_key, sizeof(iv)); 322 323 sg_init_one(&sg, txb->data, txb->len); 324 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 325 skcipher_request_set_callback(req, 0, NULL, NULL); 326 skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x); 327 ret = crypto_skcipher_encrypt(req); 328 skcipher_request_zero(req); 329 return ret; 330 } 331 332 /* 333 * checksum an RxRPC packet header 334 */ 335 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 336 { 337 struct skcipher_request *req; 338 struct rxrpc_crypt iv; 339 struct scatterlist sg; 340 union { 341 __be32 buf[2]; 342 } crypto __aligned(8); 343 u32 x, y; 344 int ret; 345 346 _enter("{%d{%x}},{#%u},%u,", 347 call->debug_id, key_serial(call->conn->key), 348 txb->seq, txb->len); 349 350 if (!call->conn->rxkad.cipher) 351 return 0; 352 353 ret = key_validate(call->conn->key); 354 if (ret < 0) 355 return ret; 356 357 req = rxkad_get_call_crypto(call); 358 if (!req) 359 return -ENOMEM; 360 361 /* continue encrypting from where we left off */ 362 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 363 364 /* calculate the security checksum */ 365 x = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 366 x |= txb->seq & 0x3fffffff; 367 crypto.buf[0] = txb->wire.callNumber; 368 crypto.buf[1] = htonl(x); 369 370 sg_init_one(&sg, crypto.buf, 8); 371 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 372 skcipher_request_set_callback(req, 0, NULL, NULL); 373 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 374 crypto_skcipher_encrypt(req); 375 skcipher_request_zero(req); 376 377 y = ntohl(crypto.buf[1]); 378 y = (y >> 16) & 0xffff; 379 if (y == 0) 380 y = 1; /* zero checksums are not permitted */ 381 txb->wire.cksum = htons(y); 382 383 switch (call->conn->security_level) { 384 case RXRPC_SECURITY_PLAIN: 385 ret = 0; 386 break; 387 case RXRPC_SECURITY_AUTH: 388 ret = rxkad_secure_packet_auth(call, txb, req); 389 break; 390 case RXRPC_SECURITY_ENCRYPT: 391 ret = rxkad_secure_packet_encrypt(call, txb, req); 392 break; 393 default: 394 ret = -EPERM; 395 break; 396 } 397 398 skcipher_request_free(req); 399 _leave(" = %d [set %x]", ret, y); 400 return ret; 401 } 402 403 /* 404 * decrypt partial encryption on a packet (level 1 security) 405 */ 406 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb, 407 rxrpc_seq_t seq, 408 struct skcipher_request *req) 409 { 410 struct rxkad_level1_hdr sechdr; 411 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 412 struct rxrpc_crypt iv; 413 struct scatterlist sg[16]; 414 u32 data_size, buf; 415 u16 check; 416 int ret; 417 418 _enter(""); 419 420 if (sp->len < 8) 421 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 422 rxkad_abort_1_short_header); 423 424 /* Decrypt the skbuff in-place. TODO: We really want to decrypt 425 * directly into the target buffer. 426 */ 427 sg_init_table(sg, ARRAY_SIZE(sg)); 428 ret = skb_to_sgvec(skb, sg, sp->offset, 8); 429 if (unlikely(ret < 0)) 430 return ret; 431 432 /* start the decryption afresh */ 433 memset(&iv, 0, sizeof(iv)); 434 435 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 436 skcipher_request_set_callback(req, 0, NULL, NULL); 437 skcipher_request_set_crypt(req, sg, sg, 8, iv.x); 438 crypto_skcipher_decrypt(req); 439 skcipher_request_zero(req); 440 441 /* Extract the decrypted packet length */ 442 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) 443 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 444 rxkad_abort_1_short_encdata); 445 sp->offset += sizeof(sechdr); 446 sp->len -= sizeof(sechdr); 447 448 buf = ntohl(sechdr.data_size); 449 data_size = buf & 0xffff; 450 451 check = buf >> 16; 452 check ^= seq ^ call->call_id; 453 check &= 0xffff; 454 if (check != 0) 455 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 456 rxkad_abort_1_short_check); 457 if (data_size > sp->len) 458 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 459 rxkad_abort_1_short_data); 460 sp->len = data_size; 461 462 _leave(" = 0 [dlen=%x]", data_size); 463 return 0; 464 } 465 466 /* 467 * wholly decrypt a packet (level 2 security) 468 */ 469 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb, 470 rxrpc_seq_t seq, 471 struct skcipher_request *req) 472 { 473 const struct rxrpc_key_token *token; 474 struct rxkad_level2_hdr sechdr; 475 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 476 struct rxrpc_crypt iv; 477 struct scatterlist _sg[4], *sg; 478 u32 data_size, buf; 479 u16 check; 480 int nsg, ret; 481 482 _enter(",{%d}", sp->len); 483 484 if (sp->len < 8) 485 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 486 rxkad_abort_2_short_header); 487 488 /* Decrypt the skbuff in-place. TODO: We really want to decrypt 489 * directly into the target buffer. 490 */ 491 sg = _sg; 492 nsg = skb_shinfo(skb)->nr_frags + 1; 493 if (nsg <= 4) { 494 nsg = 4; 495 } else { 496 sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO); 497 if (!sg) 498 return -ENOMEM; 499 } 500 501 sg_init_table(sg, nsg); 502 ret = skb_to_sgvec(skb, sg, sp->offset, sp->len); 503 if (unlikely(ret < 0)) { 504 if (sg != _sg) 505 kfree(sg); 506 return ret; 507 } 508 509 /* decrypt from the session key */ 510 token = call->conn->key->payload.data[0]; 511 memcpy(&iv, token->kad->session_key, sizeof(iv)); 512 513 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 514 skcipher_request_set_callback(req, 0, NULL, NULL); 515 skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x); 516 crypto_skcipher_decrypt(req); 517 skcipher_request_zero(req); 518 if (sg != _sg) 519 kfree(sg); 520 521 /* Extract the decrypted packet length */ 522 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) 523 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 524 rxkad_abort_2_short_len); 525 sp->offset += sizeof(sechdr); 526 sp->len -= sizeof(sechdr); 527 528 buf = ntohl(sechdr.data_size); 529 data_size = buf & 0xffff; 530 531 check = buf >> 16; 532 check ^= seq ^ call->call_id; 533 check &= 0xffff; 534 if (check != 0) 535 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 536 rxkad_abort_2_short_check); 537 538 if (data_size > sp->len) 539 return rxrpc_abort_eproto(call, skb, RXKADDATALEN, 540 rxkad_abort_2_short_data); 541 542 sp->len = data_size; 543 _leave(" = 0 [dlen=%x]", data_size); 544 return 0; 545 } 546 547 /* 548 * Verify the security on a received packet and the subpackets therein. 549 */ 550 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb) 551 { 552 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 553 struct skcipher_request *req; 554 struct rxrpc_crypt iv; 555 struct scatterlist sg; 556 union { 557 __be32 buf[2]; 558 } crypto __aligned(8); 559 rxrpc_seq_t seq = sp->hdr.seq; 560 int ret; 561 u16 cksum; 562 u32 x, y; 563 564 _enter("{%d{%x}},{#%u}", 565 call->debug_id, key_serial(call->conn->key), seq); 566 567 if (!call->conn->rxkad.cipher) 568 return 0; 569 570 req = rxkad_get_call_crypto(call); 571 if (!req) 572 return -ENOMEM; 573 574 /* continue encrypting from where we left off */ 575 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); 576 577 /* validate the security checksum */ 578 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); 579 x |= seq & 0x3fffffff; 580 crypto.buf[0] = htonl(call->call_id); 581 crypto.buf[1] = htonl(x); 582 583 sg_init_one(&sg, crypto.buf, 8); 584 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); 585 skcipher_request_set_callback(req, 0, NULL, NULL); 586 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); 587 crypto_skcipher_encrypt(req); 588 skcipher_request_zero(req); 589 590 y = ntohl(crypto.buf[1]); 591 cksum = (y >> 16) & 0xffff; 592 if (cksum == 0) 593 cksum = 1; /* zero checksums are not permitted */ 594 595 if (cksum != sp->hdr.cksum) { 596 ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, 597 rxkad_abort_bad_checksum); 598 goto out; 599 } 600 601 switch (call->conn->security_level) { 602 case RXRPC_SECURITY_PLAIN: 603 ret = 0; 604 break; 605 case RXRPC_SECURITY_AUTH: 606 ret = rxkad_verify_packet_1(call, skb, seq, req); 607 break; 608 case RXRPC_SECURITY_ENCRYPT: 609 ret = rxkad_verify_packet_2(call, skb, seq, req); 610 break; 611 default: 612 ret = -ENOANO; 613 break; 614 } 615 616 out: 617 skcipher_request_free(req); 618 return ret; 619 } 620 621 /* 622 * issue a challenge 623 */ 624 static int rxkad_issue_challenge(struct rxrpc_connection *conn) 625 { 626 struct rxkad_challenge challenge; 627 struct rxrpc_wire_header whdr; 628 struct msghdr msg; 629 struct kvec iov[2]; 630 size_t len; 631 u32 serial; 632 int ret; 633 634 _enter("{%d}", conn->debug_id); 635 636 get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce)); 637 638 challenge.version = htonl(2); 639 challenge.nonce = htonl(conn->rxkad.nonce); 640 challenge.min_level = htonl(0); 641 challenge.__padding = 0; 642 643 msg.msg_name = &conn->peer->srx.transport; 644 msg.msg_namelen = conn->peer->srx.transport_len; 645 msg.msg_control = NULL; 646 msg.msg_controllen = 0; 647 msg.msg_flags = 0; 648 649 whdr.epoch = htonl(conn->proto.epoch); 650 whdr.cid = htonl(conn->proto.cid); 651 whdr.callNumber = 0; 652 whdr.seq = 0; 653 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE; 654 whdr.flags = conn->out_clientflag; 655 whdr.userStatus = 0; 656 whdr.securityIndex = conn->security_ix; 657 whdr._rsvd = 0; 658 whdr.serviceId = htons(conn->service_id); 659 660 iov[0].iov_base = &whdr; 661 iov[0].iov_len = sizeof(whdr); 662 iov[1].iov_base = &challenge; 663 iov[1].iov_len = sizeof(challenge); 664 665 len = iov[0].iov_len + iov[1].iov_len; 666 667 serial = atomic_inc_return(&conn->serial); 668 whdr.serial = htonl(serial); 669 670 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len); 671 if (ret < 0) { 672 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 673 rxrpc_tx_point_rxkad_challenge); 674 return -EAGAIN; 675 } 676 677 conn->peer->last_tx_at = ktime_get_seconds(); 678 trace_rxrpc_tx_packet(conn->debug_id, &whdr, 679 rxrpc_tx_point_rxkad_challenge); 680 _leave(" = 0"); 681 return 0; 682 } 683 684 /* 685 * send a Kerberos security response 686 */ 687 static int rxkad_send_response(struct rxrpc_connection *conn, 688 struct rxrpc_host_header *hdr, 689 struct rxkad_response *resp, 690 const struct rxkad_key *s2) 691 { 692 struct rxrpc_wire_header whdr; 693 struct msghdr msg; 694 struct kvec iov[3]; 695 size_t len; 696 u32 serial; 697 int ret; 698 699 _enter(""); 700 701 msg.msg_name = &conn->peer->srx.transport; 702 msg.msg_namelen = conn->peer->srx.transport_len; 703 msg.msg_control = NULL; 704 msg.msg_controllen = 0; 705 msg.msg_flags = 0; 706 707 memset(&whdr, 0, sizeof(whdr)); 708 whdr.epoch = htonl(hdr->epoch); 709 whdr.cid = htonl(hdr->cid); 710 whdr.type = RXRPC_PACKET_TYPE_RESPONSE; 711 whdr.flags = conn->out_clientflag; 712 whdr.securityIndex = hdr->securityIndex; 713 whdr.serviceId = htons(hdr->serviceId); 714 715 iov[0].iov_base = &whdr; 716 iov[0].iov_len = sizeof(whdr); 717 iov[1].iov_base = resp; 718 iov[1].iov_len = sizeof(*resp); 719 iov[2].iov_base = (void *)s2->ticket; 720 iov[2].iov_len = s2->ticket_len; 721 722 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len; 723 724 serial = atomic_inc_return(&conn->serial); 725 whdr.serial = htonl(serial); 726 727 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len); 728 if (ret < 0) { 729 trace_rxrpc_tx_fail(conn->debug_id, serial, ret, 730 rxrpc_tx_point_rxkad_response); 731 return -EAGAIN; 732 } 733 734 conn->peer->last_tx_at = ktime_get_seconds(); 735 _leave(" = 0"); 736 return 0; 737 } 738 739 /* 740 * calculate the response checksum 741 */ 742 static void rxkad_calc_response_checksum(struct rxkad_response *response) 743 { 744 u32 csum = 1000003; 745 int loop; 746 u8 *p = (u8 *) response; 747 748 for (loop = sizeof(*response); loop > 0; loop--) 749 csum = csum * 0x10204081 + *p++; 750 751 response->encrypted.checksum = htonl(csum); 752 } 753 754 /* 755 * encrypt the response packet 756 */ 757 static int rxkad_encrypt_response(struct rxrpc_connection *conn, 758 struct rxkad_response *resp, 759 const struct rxkad_key *s2) 760 { 761 struct skcipher_request *req; 762 struct rxrpc_crypt iv; 763 struct scatterlist sg[1]; 764 765 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS); 766 if (!req) 767 return -ENOMEM; 768 769 /* continue encrypting from where we left off */ 770 memcpy(&iv, s2->session_key, sizeof(iv)); 771 772 sg_init_table(sg, 1); 773 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); 774 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher); 775 skcipher_request_set_callback(req, 0, NULL, NULL); 776 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); 777 crypto_skcipher_encrypt(req); 778 skcipher_request_free(req); 779 return 0; 780 } 781 782 /* 783 * respond to a challenge packet 784 */ 785 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn, 786 struct sk_buff *skb) 787 { 788 const struct rxrpc_key_token *token; 789 struct rxkad_challenge challenge; 790 struct rxkad_response *resp; 791 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 792 u32 version, nonce, min_level; 793 int ret = -EPROTO; 794 795 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key)); 796 797 if (!conn->key) 798 return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO, 799 rxkad_abort_chall_no_key); 800 801 ret = key_validate(conn->key); 802 if (ret < 0) 803 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, 804 rxkad_abort_chall_key_expired); 805 806 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 807 &challenge, sizeof(challenge)) < 0) 808 return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 809 rxkad_abort_chall_short); 810 811 version = ntohl(challenge.version); 812 nonce = ntohl(challenge.nonce); 813 min_level = ntohl(challenge.min_level); 814 815 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level); 816 817 if (version != RXKAD_VERSION) 818 return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, 819 rxkad_abort_chall_version); 820 821 if (conn->security_level < min_level) 822 return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES, 823 rxkad_abort_chall_level); 824 825 token = conn->key->payload.data[0]; 826 827 /* build the response packet */ 828 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); 829 if (!resp) 830 return -ENOMEM; 831 832 resp->version = htonl(RXKAD_VERSION); 833 resp->encrypted.epoch = htonl(conn->proto.epoch); 834 resp->encrypted.cid = htonl(conn->proto.cid); 835 resp->encrypted.securityIndex = htonl(conn->security_ix); 836 resp->encrypted.inc_nonce = htonl(nonce + 1); 837 resp->encrypted.level = htonl(conn->security_level); 838 resp->kvno = htonl(token->kad->kvno); 839 resp->ticket_len = htonl(token->kad->ticket_len); 840 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter); 841 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter); 842 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter); 843 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter); 844 845 /* calculate the response checksum and then do the encryption */ 846 rxkad_calc_response_checksum(resp); 847 ret = rxkad_encrypt_response(conn, resp, token->kad); 848 if (ret == 0) 849 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad); 850 kfree(resp); 851 return ret; 852 } 853 854 /* 855 * decrypt the kerberos IV ticket in the response 856 */ 857 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn, 858 struct key *server_key, 859 struct sk_buff *skb, 860 void *ticket, size_t ticket_len, 861 struct rxrpc_crypt *_session_key, 862 time64_t *_expiry) 863 { 864 struct skcipher_request *req; 865 struct rxrpc_crypt iv, key; 866 struct scatterlist sg[1]; 867 struct in_addr addr; 868 unsigned int life; 869 time64_t issue, now; 870 bool little_endian; 871 u8 *p, *q, *name, *end; 872 873 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key)); 874 875 *_expiry = 0; 876 877 ASSERT(server_key->payload.data[0] != NULL); 878 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0); 879 880 memcpy(&iv, &server_key->payload.data[2], sizeof(iv)); 881 882 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS); 883 if (!req) 884 return -ENOMEM; 885 886 sg_init_one(&sg[0], ticket, ticket_len); 887 skcipher_request_set_callback(req, 0, NULL, NULL); 888 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x); 889 crypto_skcipher_decrypt(req); 890 skcipher_request_free(req); 891 892 p = ticket; 893 end = p + ticket_len; 894 895 #define Z(field, fieldl) \ 896 ({ \ 897 u8 *__str = p; \ 898 q = memchr(p, 0, end - p); \ 899 if (!q || q - p > field##_SZ) \ 900 return rxrpc_abort_conn( \ 901 conn, skb, RXKADBADTICKET, -EPROTO, \ 902 rxkad_abort_resp_tkt_##fieldl); \ 903 for (; p < q; p++) \ 904 if (!isprint(*p)) \ 905 return rxrpc_abort_conn( \ 906 conn, skb, RXKADBADTICKET, -EPROTO, \ 907 rxkad_abort_resp_tkt_##fieldl); \ 908 p++; \ 909 __str; \ 910 }) 911 912 /* extract the ticket flags */ 913 _debug("KIV FLAGS: %x", *p); 914 little_endian = *p & 1; 915 p++; 916 917 /* extract the authentication name */ 918 name = Z(ANAME, aname); 919 _debug("KIV ANAME: %s", name); 920 921 /* extract the principal's instance */ 922 name = Z(INST, inst); 923 _debug("KIV INST : %s", name); 924 925 /* extract the principal's authentication domain */ 926 name = Z(REALM, realm); 927 _debug("KIV REALM: %s", name); 928 929 if (end - p < 4 + 8 + 4 + 2) 930 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO, 931 rxkad_abort_resp_tkt_short); 932 933 /* get the IPv4 address of the entity that requested the ticket */ 934 memcpy(&addr, p, sizeof(addr)); 935 p += 4; 936 _debug("KIV ADDR : %pI4", &addr); 937 938 /* get the session key from the ticket */ 939 memcpy(&key, p, sizeof(key)); 940 p += 8; 941 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1])); 942 memcpy(_session_key, &key, sizeof(key)); 943 944 /* get the ticket's lifetime */ 945 life = *p++ * 5 * 60; 946 _debug("KIV LIFE : %u", life); 947 948 /* get the issue time of the ticket */ 949 if (little_endian) { 950 __le32 stamp; 951 memcpy(&stamp, p, 4); 952 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp)); 953 } else { 954 __be32 stamp; 955 memcpy(&stamp, p, 4); 956 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp)); 957 } 958 p += 4; 959 now = ktime_get_real_seconds(); 960 _debug("KIV ISSUE: %llx [%llx]", issue, now); 961 962 /* check the ticket is in date */ 963 if (issue > now) 964 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED, 965 rxkad_abort_resp_tkt_future); 966 if (issue < now - life) 967 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED, 968 rxkad_abort_resp_tkt_expired); 969 970 *_expiry = issue + life; 971 972 /* get the service name */ 973 name = Z(SNAME, sname); 974 _debug("KIV SNAME: %s", name); 975 976 /* get the service instance name */ 977 name = Z(INST, sinst); 978 _debug("KIV SINST: %s", name); 979 return 0; 980 } 981 982 /* 983 * decrypt the response packet 984 */ 985 static void rxkad_decrypt_response(struct rxrpc_connection *conn, 986 struct rxkad_response *resp, 987 const struct rxrpc_crypt *session_key) 988 { 989 struct skcipher_request *req = rxkad_ci_req; 990 struct scatterlist sg[1]; 991 struct rxrpc_crypt iv; 992 993 _enter(",,%08x%08x", 994 ntohl(session_key->n[0]), ntohl(session_key->n[1])); 995 996 mutex_lock(&rxkad_ci_mutex); 997 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x, 998 sizeof(*session_key)) < 0) 999 BUG(); 1000 1001 memcpy(&iv, session_key, sizeof(iv)); 1002 1003 sg_init_table(sg, 1); 1004 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); 1005 skcipher_request_set_sync_tfm(req, rxkad_ci); 1006 skcipher_request_set_callback(req, 0, NULL, NULL); 1007 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); 1008 crypto_skcipher_decrypt(req); 1009 skcipher_request_zero(req); 1010 1011 mutex_unlock(&rxkad_ci_mutex); 1012 1013 _leave(""); 1014 } 1015 1016 /* 1017 * verify a response 1018 */ 1019 static int rxkad_verify_response(struct rxrpc_connection *conn, 1020 struct sk_buff *skb) 1021 { 1022 struct rxkad_response *response; 1023 struct rxrpc_skb_priv *sp = rxrpc_skb(skb); 1024 struct rxrpc_crypt session_key; 1025 struct key *server_key; 1026 time64_t expiry; 1027 void *ticket; 1028 u32 version, kvno, ticket_len, level; 1029 __be32 csum; 1030 int ret, i; 1031 1032 _enter("{%d}", conn->debug_id); 1033 1034 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0); 1035 if (IS_ERR(server_key)) { 1036 ret = PTR_ERR(server_key); 1037 switch (ret) { 1038 case -ENOKEY: 1039 return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret, 1040 rxkad_abort_resp_nokey); 1041 case -EKEYEXPIRED: 1042 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, 1043 rxkad_abort_resp_key_expired); 1044 default: 1045 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret, 1046 rxkad_abort_resp_key_rejected); 1047 } 1048 } 1049 1050 ret = -ENOMEM; 1051 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); 1052 if (!response) 1053 goto temporary_error; 1054 1055 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), 1056 response, sizeof(*response)) < 0) { 1057 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 1058 rxkad_abort_resp_short); 1059 goto protocol_error; 1060 } 1061 1062 version = ntohl(response->version); 1063 ticket_len = ntohl(response->ticket_len); 1064 kvno = ntohl(response->kvno); 1065 1066 trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len); 1067 1068 if (version != RXKAD_VERSION) { 1069 rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, 1070 rxkad_abort_resp_version); 1071 goto protocol_error; 1072 } 1073 1074 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) { 1075 rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO, 1076 rxkad_abort_resp_tkt_len); 1077 goto protocol_error; 1078 } 1079 1080 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) { 1081 rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO, 1082 rxkad_abort_resp_unknown_tkt); 1083 goto protocol_error; 1084 } 1085 1086 /* extract the kerberos ticket and decrypt and decode it */ 1087 ret = -ENOMEM; 1088 ticket = kmalloc(ticket_len, GFP_NOFS); 1089 if (!ticket) 1090 goto temporary_error_free_resp; 1091 1092 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response), 1093 ticket, ticket_len) < 0) { 1094 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, 1095 rxkad_abort_resp_short_tkt); 1096 goto protocol_error; 1097 } 1098 1099 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len, 1100 &session_key, &expiry); 1101 if (ret < 0) 1102 goto temporary_error_free_ticket; 1103 1104 /* use the session key from inside the ticket to decrypt the 1105 * response */ 1106 rxkad_decrypt_response(conn, response, &session_key); 1107 1108 if (ntohl(response->encrypted.epoch) != conn->proto.epoch || 1109 ntohl(response->encrypted.cid) != conn->proto.cid || 1110 ntohl(response->encrypted.securityIndex) != conn->security_ix) { 1111 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1112 rxkad_abort_resp_bad_param); 1113 goto protocol_error_free; 1114 } 1115 1116 csum = response->encrypted.checksum; 1117 response->encrypted.checksum = 0; 1118 rxkad_calc_response_checksum(response); 1119 if (response->encrypted.checksum != csum) { 1120 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1121 rxkad_abort_resp_bad_checksum); 1122 goto protocol_error_free; 1123 } 1124 1125 for (i = 0; i < RXRPC_MAXCALLS; i++) { 1126 u32 call_id = ntohl(response->encrypted.call_id[i]); 1127 u32 counter = READ_ONCE(conn->channels[i].call_counter); 1128 1129 if (call_id > INT_MAX) { 1130 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1131 rxkad_abort_resp_bad_callid); 1132 goto protocol_error_free; 1133 } 1134 1135 if (call_id < counter) { 1136 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1137 rxkad_abort_resp_call_ctr); 1138 goto protocol_error_free; 1139 } 1140 1141 if (call_id > counter) { 1142 if (conn->channels[i].call) { 1143 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, 1144 rxkad_abort_resp_call_state); 1145 goto protocol_error_free; 1146 } 1147 conn->channels[i].call_counter = call_id; 1148 } 1149 } 1150 1151 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) { 1152 rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO, 1153 rxkad_abort_resp_ooseq); 1154 goto protocol_error_free; 1155 } 1156 1157 level = ntohl(response->encrypted.level); 1158 if (level > RXRPC_SECURITY_ENCRYPT) { 1159 rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO, 1160 rxkad_abort_resp_level); 1161 goto protocol_error_free; 1162 } 1163 conn->security_level = level; 1164 1165 /* create a key to hold the security data and expiration time - after 1166 * this the connection security can be handled in exactly the same way 1167 * as for a client connection */ 1168 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno); 1169 if (ret < 0) 1170 goto temporary_error_free_ticket; 1171 1172 kfree(ticket); 1173 kfree(response); 1174 _leave(" = 0"); 1175 return 0; 1176 1177 protocol_error_free: 1178 kfree(ticket); 1179 protocol_error: 1180 kfree(response); 1181 key_put(server_key); 1182 return -EPROTO; 1183 1184 temporary_error_free_ticket: 1185 kfree(ticket); 1186 temporary_error_free_resp: 1187 kfree(response); 1188 temporary_error: 1189 /* Ignore the response packet if we got a temporary error such as 1190 * ENOMEM. We just want to send the challenge again. Note that we 1191 * also come out this way if the ticket decryption fails. 1192 */ 1193 key_put(server_key); 1194 return ret; 1195 } 1196 1197 /* 1198 * clear the connection security 1199 */ 1200 static void rxkad_clear(struct rxrpc_connection *conn) 1201 { 1202 _enter(""); 1203 1204 if (conn->rxkad.cipher) 1205 crypto_free_sync_skcipher(conn->rxkad.cipher); 1206 } 1207 1208 /* 1209 * Initialise the rxkad security service. 1210 */ 1211 static int rxkad_init(void) 1212 { 1213 struct crypto_sync_skcipher *tfm; 1214 struct skcipher_request *req; 1215 1216 /* pin the cipher we need so that the crypto layer doesn't invoke 1217 * keventd to go get it */ 1218 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); 1219 if (IS_ERR(tfm)) 1220 return PTR_ERR(tfm); 1221 1222 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL); 1223 if (!req) 1224 goto nomem_tfm; 1225 1226 rxkad_ci_req = req; 1227 rxkad_ci = tfm; 1228 return 0; 1229 1230 nomem_tfm: 1231 crypto_free_sync_skcipher(tfm); 1232 return -ENOMEM; 1233 } 1234 1235 /* 1236 * Clean up the rxkad security service. 1237 */ 1238 static void rxkad_exit(void) 1239 { 1240 crypto_free_sync_skcipher(rxkad_ci); 1241 skcipher_request_free(rxkad_ci_req); 1242 } 1243 1244 /* 1245 * RxRPC Kerberos-based security 1246 */ 1247 const struct rxrpc_security rxkad = { 1248 .name = "rxkad", 1249 .security_index = RXRPC_SECURITY_RXKAD, 1250 .no_key_abort = RXKADUNKNOWNKEY, 1251 .init = rxkad_init, 1252 .exit = rxkad_exit, 1253 .preparse_server_key = rxkad_preparse_server_key, 1254 .free_preparse_server_key = rxkad_free_preparse_server_key, 1255 .destroy_server_key = rxkad_destroy_server_key, 1256 .init_connection_security = rxkad_init_connection_security, 1257 .how_much_data = rxkad_how_much_data, 1258 .secure_packet = rxkad_secure_packet, 1259 .verify_packet = rxkad_verify_packet, 1260 .free_call_crypto = rxkad_free_call_crypto, 1261 .issue_challenge = rxkad_issue_challenge, 1262 .respond_to_challenge = rxkad_respond_to_challenge, 1263 .verify_response = rxkad_verify_response, 1264 .clear = rxkad_clear, 1265 }; 1266